qed: LL2 to use packed information for tx

First step in revising the LL2 interface, this declares
qed_ll2_tx_pkt_info as part of the ll2 interface, and uses it for
transmission instead of receiving lots of parameters.

Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>